If you want to make things easier or more challenging for your learner, you can use the learning settings to change the lesson time, the number of A grades needed to move up a stage, and the percentage required to get an A or A* score.
Here's what to do:
Switch User to you and go into Settings for Bosses.
Select Learning Settings
then Change Learner Settings. (Find out more about changing the learner course here.)
And you'll see all the options here to reduce or increase the time your learner has to complete each lesson, how many A* grades are needed for a stage shortcut, and what percentage of correct answers are required for an A or A* grade.